ArcMap

Create Underpass

Summary

Allows intersecting lines to be displayed as underpassing one another by creating bridge parapets and masks to cover the underlying road segment.

Illustration

Illustration of Create Underpass tool
Creating underpass with different wing types

Usage

  • Requires intersecting line features symbolized with stroke representations as inputs.

  • This tool is identical to the Create Overpass tool except that the Expression parameter selects from the Input Below Features With Representations parameter in this tool, and selects from the Input Above Features With Representations parameter in the Create Overpass tool.

  • The Input Above Features With Representations layer can be the same as the Input Below Features With Representations layer in the case of self-overlapping features. When Input Above and Input Below representations are the same, an SQL expression is required for further refinement of feature selection.

Syntax

CreateUnderpass(in_above_features, in_below_features, margin_along, margin_across, out_underpass_feature_class, out_mask_relationship_class, {where_clause}, {out_decoration_feature_class}, {wing_type}, {wing_tick_length})
ParameterExplanationData Type
in_above_features

The input line feature layer containing stroke representations that intersect—and will be symbolized as passing above—stroke representations in the Input Below Features With Representations parameter.

Layer
in_below_features

The input line feature layer containing stroke representations that intersect—and will be symbolized as passing below—stroke representations in the Input Above Features With Representations parameter. These features will be masked by the polygons created in the Output Underpass Feature Class parameter.

Layer
margin_along

Sets the length of the mask polygons along the Input Above Features With Representations parameter by specifying the distance in page units that the mask should extend beyond the width of the stroke symbol of the Input Below Features With Representations parameter. The Margin Along parameter must be specified, and it must be greater than or equal to zero. Choose a page unit for the margin; the default is points.

Linear Unit
margin_across

Sets the width of the mask polygons across the Input Above Features With Representations parameter by specifying the distance in page units that the mask should extend beyond the width of the stroke symbol of the Input Below Features With Representations parameter. The Margin Across parameter must be specified, and it must be greater than or equal to zero. Choose a page unit for the margin; the default is points.

Linear Unit
out_underpass_feature_class

The output feature class that will be created to store polygons to mask the Input Below Features With Representations parameter.

Feature Class
out_mask_relationship_class

The output relationship class that is created to store links between underpass mask polygons and the lines of the Input Below Features With Representations parameter.

Relationship Class
where_clause
(Optional)

An SQL expression used to select a subset of features in the Input Above Features With Representations parameter.

Use quotation marks, "MY_FIELD", or if you're querying personal geodatabases, enclose fields in square brackets: [MY_FIELD]

See SQL reference for query expressions used in ArcGIS for more information on SQL syntax.

SQL Expression
out_decoration_feature_class
(Optional)

The output line feature class that will be created to store parapet features.

Feature Class
wing_type
(Optional)

Specifies the wing style of the parapet features.

  • ANGLED —Specifies that the wing tick of the parapet will be angled between the Input Above Features parameter and the Input Below Features parameter. This is the default.
  • PARALLEL —Specifies that the wing tick of the overpass wing will be parallel to the Input Below Features parameter.
  • NONE —Specifies that no wing ticks will be created on the parapets.
String
wing_tick_length
(Optional)

Sets the length of the parapet wings in page units. The length must be greater than or equal to zero; the default length is 1. Choose a page unit (points, millimeters, and so on) for the length; the default is points. This parameter does not apply to the Wing Type of NONE.

Linear Unit

Code sample

CreateUnderpass example 1 (Python window)

The following Python window script demonstrates how to use the CreateUnderpass tool in immediate mode.

import arcpy
arcpy.env.workspace = "C:\data"
arcpy.env.referenceScale = "50000"
arcpy.CreateUnderpass_cartography("roads.lyr", "railroads.lyr", "2 Points", "1 Points",
                                 "cartography.gdb/transportation/under_mask_fc",
                                 "cartography.gdb/transportation/under_mask_rc", "'RelationshipToSurface' = 3",
                                 "cartography.gdb/transportation/tunnel", "PARALLEL", "1 Points")
CreateUnderpass example 2 (stand-alone script)

This stand-alone script shows an example of using the CreateUnderpass tool.

# Name: CreateUnderpass_standalone_script.py
# Description: creates a mask where one feature
#              is visually below another feature
 
# Import system modules
import arcpy
from arcpy import env

# Set environment settings
env.workspace = "C:/data"
env.referenceScale = "50000"

# Set local variables
in_above_features = "roads.lyr"
in_below_features = "railroads.lyr"
margin_along = "2 Points"
margin_across = "1 Points"
out_overpass_feature_class = "cartography.gdb/trans/under_mask_fc"
out_mask_relationship_class = "cartography.gdb/trans/under_mask_rc"
where_clause = "'RelationshipToSurface' = 3"
out_decoration_feature_class = "cartography.gdb/trans/tunnel"
wing_type = "PARALLEL"
wing_tick_length = "1 Points"

# Execute Create Underpass
arcpy.CreateUnderpass_cartography(in_above_features,
                                  in_below_features,
                                  margin_along,
                                  margin_across,
                                  out_overpass_feature_class,
                                  out_mask_relationship_class,
                                  where_clause,
                                  out_decoration_feature_class,
                                  wing_type,
                                  wing_tick_length)

Environments

Licensing information

  • Basic: No
  • Standard: No
  • Advanced: Yes

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